diff --git a/SConscript.prodtest b/SConscript.prodtest
index 769499392a..7edabeec34 100644
--- a/SConscript.prodtest
+++ b/SConscript.prodtest
@@ -78,6 +78,15 @@ env.Replace(
 env.Replace(
     TREZOR_MODEL=env.get('ENV').get('TREZOR_MODEL', 'T'), )
 
+if env.get('TREZOR_MODEL') == 'T':
+    CPU_ASFLAGS = '-mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16'
+    CPU_CCFLAGS = '-mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -mtune=cortex-m4 '
+    CPU_MODEL   = 'STM32F427xx'
+else:
+    CPU_ASFLAGS = '-mthumb -mcpu=cortex-m3 -mfloat-abi=soft'
+    CPU_CCFLAGS = '-mthumb -mtune=cortex-m3 -mcpu=cortex-m3 -mfloat-abi=soft '
+    CPU_MODEL   = 'STM32F405xx'
+
 env.Replace(
     COPT=env.get('ENV').get('OPTIMIZE', '-Os'),
     CCFLAGS='$COPT '